The present invention is directed generally to flexible covers for open top load-carrying boxes on land vehicles, and more specifically to power driven apparatus for deploying and retrieving such flexible covers over the open top of the load-carrying boxes. The invention has special utility in connection with trucks and trailers used to carry loads of particulate materials such as grain, feed, coal, gravel, and the like.
A variety of apparatus for applying flexible covers is known from the prior art. For example, Michel, U.S. Pat. No. 5,002,328, discloses a motorized drive system for covering and uncovering the top of an open truck box. A lateral edge of the flexible cover is fixed to one side of the box while the other lateral edge is attached to a roll tube. A reversible rotary motor rotates the roll tube to either remove the cover from the top of the box or to deploy the cover over the box. The position of the roll tube is, in part, controlled by an extensible arm and, in part, by a cable return mechanism adapted to apply a constant tension during the winding and unwinding of the cover over the tube.
Tsukamoto, U.S. Pat. No. 4,673,208, discloses a similar power operated cover roller mechanism involving pivotally mounted levers and a special chain and sprocket arrangement to secure the cover over the truck bed. The power is supplied to the pivotally mounted levers through power cylinders 19 and 20 coupled to the pivotally mounted levers. Klassen, U.S. Pat. No. 5,328,228, discloses yet another pivotally mounted lever assembly for rolling a cover over a truck bed and cargo. The roller is moved through a series of pulleys by virtue of a motor affixed to one side of the truck body.
Odegaard, U.S. Pat. No. 4,834,445, discloses yet another cover deployment apparatus carried by an arm which is itself pivoted to another arm coupled to one side of the container body. The motor operating the roller carrying the flexible cover is disposed at the very end of the first arm and spring tension members are employed to urge the first arm toward the fully deployed position. Fredin, U.S. Pat. No. 4,225,175 discloses yet another similar arrangement for applying a flexible cover over a container using a pivoted arm moved by a power cylinder 9.
Wilkens, U.S. Pat. No. 5,765,901, discloses a similar roll-up assembly in which a hand crank rather than a motor is employed. The hand crank is designed to be secured to the trailer on either side depending upon whether the cover is in the open or closed position. Another hand crank system is shown in Harris et al., U.S. Pat. No. 5,466,030 which exposes or covers one side of a freight container rather than an open top.
Haddad, Jr., U.S. Pat. No. 5,275,459, discloses a cover deployment mechanism for use on a trailer wherein an arm is provided on each side of the trailer, the two arms having a tie rod between them to which the flexible cover is attached. Each of the two arms include an electrically insulating spacer so that in the event of an inadvertent contact with an overhead power line, such contact should not damage any portion of the mechanism. Somewhat similar mechanisms are shown in Bailey, U.S. Pat. No. 4,893,864, and Cappello, U.S. Pat. No. 3,549,198. A double cover arrangement deployed in a similar manner is shown in Haddad, Jr., U.S. Pat. No. 5,573,295.
Despite this variety of apparatus for applying flexible covers in the prior art, a need still exists for a reliable mechanism capable of covering a load without binding using a power mechanism that can be controlled from the cab of the vehicle. It is of particular interest to have such a mechanism that can accommodate a wide variety of trucks and trailers that may have upper perimeters of varying shape and curvature.